DALLAS (AP) — Thrifty Car Rental says it’s sorry, but many customers who were offered a free one-day rental won’t be getting that after all.

The company says the offer was intended for a select group of top customers but was sent accidentally to many other people.

“We’re very sorry for any confusion our eagerness may have caused,” the chain, which is owned by Hertz Global Holdings Inc., told customers by email.

Airlines, hotels and stores occasionally post incorrect prices. When they do, they must balance the cost of honoring the mistaken price against the potential to offend bargain-loving customers.

When the dollar difference is huge, “smart companies offer an apology with some sort of salve — ‘Here’s a gift certificate,’ or ‘Here’s a 10 percent-off coupon’ to demonstrate their remorse,” said Mark Cohen, a longtime executive at Sears and other department stores who now teaches at Columbia University’s business school.

Hertz spokeswoman Paula Rivera said the offer sent out Friday night was meant for “select” members of Thrifty’s frequent-renter program, called Blue Chip. They were offered a free day after 16 days of paid rentals.

By mistake the offer went to other customers who had merely signed up to receive emails from the company, Rivera said.

“Unfortunately, this was a human error and as soon as we became aware of the mass email distribution, we took steps to correct the situation.” including the follow-up email on Saturday, she said.

The company did not say how many customers received the offer in error, so it’s impossible to estimate how much it would cost Thrifty to make good on the free rentals.

Customers who thought they were getting a nice freebie were disappointed by the reversal.

“I was kind of shocked that they rescinded the offer, even if it was a mistake,” said Alison McCarthy of Brooklyn, N.Y., who works in digital marketing. “They should have honored it — it’s just one day.”

McCarthy said last year she lucked into a mistake airfare to Israel on El Al. The airline blamed a contractor for accidentally posting fares of less than $400 instead of the usual $1,000 to $1,600 per round trip but honored the lower price. “It was awesome, and it was positive PR (public relations) for them,” she said.

Such airfare deals are less common now because the company that airlines use to publish fares has made it easier for the carriers to spot unusual prices before they’re made public, said Gary Leff, a travel blogger and co-founder of Milepoint, an online forum for frequent fliers, who avidly swap tips on mistake fares. Hotels might be more fruitful hunting ground.

Leff said that a few years ago he jumped on a nightly rate of 66 cents for a beachfront villa at a Le Meridien resort in Thailand. The hotel company had loaded the price in Ugandan shillings instead of U.S. dollars. He said the hotel gave him the room for $33, “and that included tax and a free breakfast.”

Leff’s advice: If you see a deal that sounds too good to be true, go ahead and book it but don’t be too disappointed if the company rescinds the offer.